The invention is based on a fuel supply apparatus for internal combustion engines having a fuel injection pump which includes a predetermined interior pressure for supplying a regulatable fuel injection quantity, a ventilation apparatus for the fuel injection pump and an exhaust gas recirculation means controlled by said fuel quantity. In such fuel injection pumps, it is known to perform a cooling of the distributor pump and thus of the fuel pumped by it and delivered to the injection valves, and at the same time to control the recirculation of exhaust gas from the exhaust tube to the intake tube in accordance with the quantity of fuel delivered to the injection pump or consumed by the injection pump in delivering it to the injection valves, this control being such that a sufficient quantity of fresh air for satisfactory combustion is always available to the engine. The supply of the fuel can be regulated by volumetric metering, and a maximum of power can be attained by means of this regulation without exceeding the limits for the maximum permissible toxic component of the exhaust gas.
In this connection, it is known also to associate heat exchangers with the distributor injection pump, and temperature sensors may generally be provided, which deliver fuel used for cooling purposes to a separately provided cooler of the distributor injection pump by way of separate fuel lines. The exhaust gas recirculation system associated with such fuel supply apparatus is usually regulated mechanically, and it may be designed such that a throttle valve in the intake tube progressively closes the mouth of the exhaust recirculation line, the more the throttle valve opens up in order to increase the fresh-air component. The adjustment of the throttle valve may be controlled via a hydraulic motor by a comparative regulating device, which ascertains an actual value for the quantity of fresh air delivered to the engine, perhaps with the aid of a baffle valve, and compares this value with the fuel quantity delivered to the distributor injection pump, this comparison being effected with the aid of a differential valve. In so doing, a so-called exhaust gas test range is defined with respect to the engine rpm, and within this range the recirculation of exhaust gas takes place, frequently being variably controlled in its magnitude; at very high engine rpm, outside the test range, it is desirable to shut off the recirculation of exhaust gas. This is often accomplished by means of a suitable control of the exhaust gas recirculation quantity in accordance with the fuel quantity supplied by the fuel injection pump. The disposition of a cooler with the associated lines for the distributor pump is complicated, however, and it is expensive both in terms of engineering effort and cost; the same disadvantages apply to regulating the exhaust gas recirculation quantity with the aid of the comparison device including a differential valve.